Severe Thunderstorm Warning 81, NWS Gaylord, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
337 AM EDT FRI OCT 4 2002

UPPER FLOW PATTERN CONSOLIDATES EARLY IN THE FORECAST PERIOD AS SPLIT
BETWEEN NORTHERN AND SOUTHERN STREAM WAVES MERGE TOGETHER OVER THE
GREAT LAKES LATER TODAY...LEADING TO AN OVERALL BROAD/LOW AMPLITUDE
LONG WAVE TROUGH ACROSS MUCH OF EASTERN NORTH AMERICA.  SEVERAL
ADDITIONAL WAVES WILL DROP INTO THE NORTHERN PLAINS DURING THE LATTER
PORTION OF THE NEAR TERM FORECAST...ONE OF WHICH IS EXPECTED TO SPIN UP
ANOTHER LOW AND BRING THAT INTO THE GREAT LAKES LATER SUNDAY.  INITIAL
FORECAST CONCERNS DEAL WITH PRECIP TIMING/QPF AND SEVERE POTENTIAL
LATER TODAY AND EARLY EVENING...AS WELL AS WINDS ESPECIALLY BEHIND COLD
FROPA THIS EVENING.  OVERNIGHT INTO SATURDAY WILL NEED TO LOOK AT
POTENTIAL FOR LAKE INDUCED SHOWERS AS 850MB TEMPERATURES PLUNGE TOWARD
0C.  TIMING OF PRECIP LATER SATURDAY NIGHT/SUNDAY IN INCREASING WAA
AHEAD OF NEXT SHORT WAVE THE FINAL HURDLE.

TODAY...06Z SURFACE MAP SHOWS 999MB LOW PRESSURE GETTING ORGANIZED NEAR
OMA WITH 6MB/3H PRESSURE FALLS TO THE NORTHEAST.  LATEST ETA RUN
CONTINUES TO STRUGGLE WITH THIS...QUICKER AVN STILL LOOKS BETTER.
REMNANTS OF LILI LIFTING INTO ARKANSAS...WITH LATEST NHC TRACK
FOLLOWING AVN IDEA CLOSELY OF PULLING SYSTEM INTO OHIO VALLEY THIS
AFTERNOON.  PRECIPITATION CONTINUES TO BLOSSOM AHEAD OF TROUGH ACROSS
MN/IA/KS...AND THIS WILL EVENTUALLY SPREAD INTO THE STATE LATER TODAY.
WILL PROBABLY START THE DAY OUT WITH SCATTERED SHOWER TYPE WORDING ALL
ZONES UNLESS RADAR TRENDS COMPEL ME TO DO OTHERWISE...THEN SPREAD
WIDESPREAD SHOWERS/THUNDERSTORMS ACROSS THE FORECAST AREA FROM LATE
MORNING THROUGH THE AFTERNOON.  KAPX 88D SHOWING SOME SCATTERED LIGHT
RAIN SHOWERS FROM THE STRAITS NORTH INTO EASTERN UPPER ASSOCIATED WITH
WEAK EAST-WEST ORIENTED SHORT WAVE MOVING NORTH...WITH STRONGER
CONVECTION POPPING FARTHER SOUTH ALONG WARM FRONT ACROSS SOUTHERN
WI/SOUTHERN LAKE MICHIGAN WHERE BETTER INSTABILITY ON 00Z SOUNDINGS
LOCATED.  HEAVY RAINFALL POTENTIAL STILL LOOKS PRETTY GOOD THOUGH
SYSTEM WILL BE RELATIVELY QUICK MOVING...WITH STRONG LOW LEVEL
CONVERGENCE/RRQ JET DYNAMICS ALONG FRONT COMBINED WITH PWS APPROACHING
2+ INCHES THANKS TO SOME INFLOW FROM LILI REMNANTS...FAIRLY
UNIDIRECTIONAL WINDS ALOFT ALLOWING FOR ECHO TRAINING...AND STRONG
WARMING ALOFT PUSHING FREEZING LEVELS TO NEAR 4KM ADD UP A POTENTIALLY
EFFICIENT RAIN MAKER WITH AMOUNTS OF 1-2 INCHES LOOKING GOOD.  SEVERE
POTENTIAL WILL ONLY BE HAMPERED BY LACK OF INSTABILITY GIVEN CLOUD
COVER AND RAINFALL.  STRONG DYNAMICS MAY BE ABLE TO MAKE UP FOR SOME OF
THIS HOWEVER (SIMILAR TO AN EARLY SEASON SEVERE WEATHER EVENT).
FORECAST HODOGRAPHS ARE VERY LONG (0-6KM SHEAR AROUND 40 M/S) WITH 50+
KT WINDS DOWN TO 925MB...AND MOST OF LOWER MICHIGAN SHOULD GET INTO THE
WARM SECTOR.  THINK MOST LIKELY MODE OF SEVERE WEATHER WOULD BE A
NARROW LINE OF THUNDERSTORMS PRODUCING DAMAGING WIND GUSTS...ESPECIALLY
IF DRY SLOT SWINGING AROUND FRONT SIDE OF TROUGH CAN GET INVOLVED.
WITH HIGH 0-6KM SHEAR VALUES WOULD ALSO NEED TO WATCH FOR SOME
SUPERCELL POTENTIAL.  HAZARDOUS WEATHER OUTLOOK WILL BE ISSUED SHORTLY
AFTER ZONES TO COVER THIS.  AS FOR WINDS TODAY...GRADIENT TIGHTENS UP
QUICKLY THIS MORNING AS SURFACE LOW LIFTS THROUGH WI...20-30 MPH FROM
THE SOUTH/SOUTHEAST STILL LOOKS GOOD.  BETTER QUESTION IS HOW HIGH CAN
GUSTS BE AHEAD OF COLD FRONT WITH 50 KT WINDS NOT FAR OFF THE
SURFACE...BUT MODEL SOUNDINGS NOT QUITE MIXED TO THE SURFACE.  BELIEVE
THAT AREAS SOUTH OF THE WARM FRONT COULD POP GUSTS CLOSE TO 40 MPH
DURING THE AFTERNOON.  TEMPERATURE NOT TOO DIFFERENT FROM CURRENT
FORECAST...65-70 EASTERN UPPER AND MOSTLY 70S NORTHERN LOWER.

TONIGHT...MAIN PRECIP BAND WILL SLIDE ON OUT OF THE AREA DURING THE
EARLY EVENING HOURS.  ANOTHER AREA OF DEEP MOISTURE WILL SLIDE ACROSS
UPPER MICHIGAN DURING THE EVENING IN DEFORMATION AXIS ON BACKSIDE OF
SHORT WAVE CROSSING THE STATE.  DESPITE DRY SLOT PUNCHING IN...WITH
STEEPING LAPSE RATES CANT RULE OUT A FEW POST FRONTAL SHOWERS ACROSS
NORTHWEST LOWER UNTIL SHORT WAVE AXIS MOVES THROUGH.  STRONG CAA BEHIND
FRONT WITH 850MB TEMPERATURES FALLING TO NEAR 0C ACROSS LAKE MICHIGAN
AND AROUND -2C ACROSS LAKE SUPERIOR...THOUGH NICE SUBSIDENCE INVERSION
DEVELOPS OVERNIGHT...WITH INVERSION BASE TEMPERATURES AROUND -5C OVER
LAKE SUPERIOR AND -3 TO -4C OVER LAKE MICHIGAN.  SO LAKE EFFECT SHOWERS
OVERNIGHT DONT LOOK TOO LIKELY UNLESS CONVECTION CAN PENETRATE TO THE
-10C LEVEL...WHICH MAY OCCUR OVER EASTERN UPPER SO WILL MAINTAIN A
CHANCE OF SHOWERS OVERNIGHT THERE...AS WELL AS THE TIP OF THE MITT
COUNTIES IN CASE SOMETHING TRIES TO SNEAK SOUTH OF THE BRIDGE.  PLENTY
OF LOW LEVEL MOISTURE BELOW INVERSION...SO WILL HANG ONTO CLOUD COVER
ALL NIGHT ACROSS THE AREA THOUGH MAY START OUT PARTLY CLOUDY AS DRY
SLOT PUSHES THROUGH.  ALONG WITH STRONG CAA SHOULD SEE A BURST OF
WIND BEHIND THE FRONT...THOUGH LOW LEVEL WIND FIELDS NOT A STRONG AS
AHEAD OF SYSTEM.  STILL 20-30 MPH WINDS LOOK REASONABLE WITH SOME
STRONGER GUSTS ALONG THE NORTHWEST FACING LAKESHORES.  WINDS WILL
DIMINISH OVERNIGHT AS GRADIENT SLACKENS.

SATURDAY/SATURDAY NIGHT...WEAK SHORT WAVE SHEARS OUT ACROSS UPPER
MICHIGAN DURING THE DAY...COMBINED WITH LAKE/DIURNAL INFLUENCES AND MID
LEVEL COOLING STEEPENING LAPSE RATES A BIT MAY BE ENOUGH TO CONTINUE
CHANCE OF SHOWERS WORDING ACROSS EASTERN UPPER AND THE STRAITS AREA.
THE REST OF NORTHERN LOWER SHOULD SEE A GOOD DEAL OF SC DEVELOP AS LAKE
CLOUDS ARE ENHANCED BY DIURNAL HEATING.  PROBLEMS CREEP IN SATURDAY
NIGHT AS MODELS HAVE VARIOUS IDEAS ON FORCING/MOISTURE ACROSS THE
AREA.  RIGHT NOW WILL FOCUS ON INCREASING LOW LEVEL WAA...WHICH SHOULD
SPREAD ADDITIONAL CLOUD COVER ACROSS THE AREA OVERNIGHT AND MAY ENHANCE
POTENTIAL FOR SOME LAKE EFFECT RAIN SHOWERS ACROSS EASTERN UPPER/
NORTHWEST LOWER OVERNIGHT.  NOT SURE IF WAA WILL BE ENOUGH TO PUSH RAIN
CHANCES INTO NORTHEAST LOWER OVERNIGHT...ETA WOULD CERTAINLY IMPLY IT
BUT THIS IS A CHANGE FROM EARLIER RUNS SO WILL SIMPLY MAINTAIN CURRENT
FORECAST (THOUGH WILL DROP MENTION OF SNOW FOR EASTERN UPPER WITH WARM
LAYER DEPTHS ABOVE 3K FEET).

SUNDAY/EXTENDED...NO CHANGES TO SUNDAY WITH LIKELY POPS STILL JUSTIFIED
AS SMALL BUT DYNAMIC SYSTEM IMPACTS THE AREA WITH ANOTHER ROUND OF RAIN
SHOWERS.

COORDINATED WITH MQT.

.APX...NONE.

JPB

MIZ008-015>036-041-042-051000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GAYLORD MI
445 AM EDT FRI OCT 4 2002

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN LOWER AND EASTERN
UPPER MICHIGAN.

.DAY ONE...

THERE IS A RISK FOR SEVERE THUNDERSTORMS ACROSS NORTHERN LOWER MICHIGAN
DURING THE AFTERNOON.  GREATEST THREAT FOR SEVERE WEATHER WILL OCCUR
EAST OF A CHEBOYGAN TO MANISTEE LINE BETWEEN 1 PM AND 8 PM.  WIND GUSTS
IN EXCESS OF 70 MPH WILL BE THE MAIN THREAT...ALONG WITH LOCALLY HEAVY
RAINFALL.

.SPOTTER CALL TO ACTION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED ACROSS NORTHERN LOWER MICHIGAN THIS
AFTERNOON.

.DAYS TWO THROUGH SEVEN...

NO HAZARDOUS WEATHER EXPECTED.  WIND GUSTS OF 30 TO 40 MPH ARE EXPECTED
BEHIND A COLD FRONT FRIDAY EVENING.

JPB